Unitary sealed piston



y 1961 v. D. DAILEY UNITARY SEALED PISTON Filed Jan. 26, 1959 FIGJ.

INVENTOR.

.DAI LEY ATTORNEYS 2,984,529 UNITARY SEALED PISTON Vacell D. Dailey, Waterford, Mich., assignor to Baldwin Rubber Company, Pontiac, Micln, a corporation of Michigan Filed Jan. 26, 1959, Ser. No. 788,972 Claims. (Cl. 309-33) The present invention relates to unitary sealed pistons and refers more particularly to a sealed piston comprismg a single element seal and cushioning member mounted on a piston body.

Prior art sealed pistons have generally been constructed of a central spacing ring, separate cups or seals and retainer rings to hold the cups or seals in place against the spacing ring. Also, in the past it has been practice to provide sealed pistons with special cushioning me-"ns such as axially extending annular sleeves and check valves acting in conjunction with mating recesses in cylinder ends in installations where cushioning of the piston in operation was desired.

The prior art structure is undesirable in many respects. It requires individual production and gathering of many parts plus a good deal of assembly time to produce such a sealed piston. With individual spacing rings, retainer plates, cup seals and cushioning apparatus the concentric assembly thereof to provide proper sealing action is difiicult. Also, such assemblies are subject to the development of leaks due to their many contacting surfaces and cup or seal surfaces are subject to distortion in assembly. Furthermore, such structure is rather complicated and expensive to produce.

It is therefore one of the objects of the present invention to provide a simplified sealed piston assembly.

Another object is to provide a single unit piston assembly for sealing and cushioning the piston in operation.

Another object is to provide a unitary sealed piston comprising an annular piston body having sealed thereto a sealing and cushioning member, said piston being capable of installation with separate cushioning means.

More specifically it is an object of the invention to provide a simplified sealed piston construction comprising a relatively rigid annular body having an annular resilient sealing and cushion member permanently afiixed thereto, the sealing and cushioning member including a plurality of peripheral sealing zones axially spaced with respect to said body member.

More specifically it is an object of the invention to provide a simplified sealed piston construction comprising a relatively rigid annular body having an annular resilient sealing and cushioning member permanently atfixed thereto, the sealing and cushioning member including a plurality of angularly spaced axially extending bosses which serve as cushioning means for the piston either alone or in conjunction with the usual cushioning means.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

Figure 1 is a longitudinal cross section taken on line 1-1 of Figure 2 of a'unitary sealed piston according to the invention in a typical installation within a cylinder.

Figure 2 is a cross section view of the cylinder and pis ton installation of Figure 1 taken on line 2-2 of Figure 1.

States Pa nt Figure 3 is a partial longitudinal cross: section of the piston and cylinder assembly of Figure 1 showing a modified piston seal.

An embodiment of a unitary sealed piston according to the invention is shown at 10 in Figure 1 in a typical in stallation thereof within a pneumatic or hydraulic cylinder generally designated 12. Piston 10 comprises a body part 14 adapted to be connected to a piston rod 16 and a resilient sealing and cushioning member 18 carried by and molded to the body part 14. The piston construction shown is provided to reduce the possibility of the piston leaking, to eliminate the chance of misalignment of distortion of the parts thereof in assembly, shorten the time required to assemble the piston, and remove the necessity of special cushioning devices in most installations.

Cylinder 12 comprises cylindrical body 20, end closures 22 and 24, sealing cap 26, piston rod 16 and cushioning means 30. The particular cylinder 12 herein shown forms no part of the present invention and will therefore be considered only briefly to illustrate a possible use of the unitary sealed piston of the invention. It should be understood in this connection that applicant does not wish to be limited to the use of his piston in combination with the particular cylinder herein described as use in pumps and other devices requiring sealed pistons is contemplated.

As shown, end closures 22 and 24 are sealed at 32 to cylindrical body 20 to provide a piston chamber 34 in which piston 10 is reciprocally positioned. The end closures 22 and 24 are provided wih recesses 36 and 38 respectively located axially and interiorly with respect to cylinder 12 and radially extending orifices 40 and 42 respectively extending between said recesses and the exterior of the assembled cylinder 12 as shown. The orifices 40 and 42 are adapted for the attachment of hydraulic or pneumatic lines (not shown) through which air or fluid may be introduced or expelled as desired for the actuation of piston 10 in the usual manner. Piston rod 16 extends through centrally located opening 44 in end closure 22, as shown. Opening 44 in end closure 22 is closed by sealing cap 26. End 46 of piston rod 16 is reduced in diameter providing shoulder 48 against which cushioning sleeve 50 may be held by means of piston 10 and cushioning sleeve 52 assembled as shown on the reduced end of rod 16 and secured in place by not 54 threaded on rod 16. Should no special cushioning means such as sleeves 50 and 52 be desired the piston 10 may be directly butted against shoulder 48 and held in position by a nut 54.

Piston 10 as shown comprises body 14 and resilient sealing and cushioning member 18. Body 14 is a relatively rigid annular disk adapted to be rigidly held by rod 16 and reciprocated within cylinder 12 thereby. Body member 14 may be made of metal, plastic, or other rigid material, molded, stamped, or otherwise formed to shape.

The resilient sealing and cushioning member 18 is molded on or otherwise sealed to body member 14 over the complete contacting surfaces thereof. Sealing and cushioning member 18 may be made of natural rubber, syntheiic rubber, such as Buna N having a Shore Durometer A scale reading of between to 85, or other similar formable resilient material. The exact material from which resilient member 18 is produced will depend on the nature of the individual installation; as for example, whether the installation is pneumatic or hydraulic. As shown, sealing and cushioning member 18 is provided with a peripheral flange 56 which is axially extending and radially outward with respect to the body member 18. Sealing and cushioning member 18 is also provided with resilient axially extending bosses or projections '58 on both sides thereof angularly spaced about raised circular portions of member 18 which are concentric with said cylinder as best shown in Figure 2 The peripheral flange 56 as shown is relatively thin in relation to the length of portions 59 and 61 thereof and has a concave or cupped radially outer surface 60 to allow fluid or air pressing against the radially inner surface of the flange 56 to seal the flange to the cylinder body 20. Edges 62 and 64 of flange 56 contact the wall of cylindrical body 20 when piston is properly mounted on piston rod 16 providing two separate annular sealing areas between the piston and cylinder. If desired in a particular installation other annular sealing areas between the piston and cylinder body may be provided by properly forming the concave outer surface of flange 56 is shown for example in Figure 3, or only a single sealing area between the piston 10 and cylinder body 20 may be provided at one side of piston body 14. The choice of the number of sealing areas between the piston 10 and the cylinder body 20 engaged thereby and therefore the configuration of flange 56 depends on the individual installation and therefore applicant does not wish to be limited to the particular embodiments of the invention as shown for illustration purposes. It should benoted that with a peripheral flange such as 56 on a resilient member 18 molded on or otherwise completely sealed to a body such as 14 there is little chance of leaking between the parts of the piston and also that assembly or replacement of the piston may be easily and quickly accomplished without distortion of the piston seal.

Bosses or projections 58 are provided on resilient member 18 as shown. The projections 58 are also resilient and serve to cushion the piston on contact of the piston with end closures 22 and 24 during reciprocation of the piston within cylinder 12. The provision of projections 58 on resilient member 18 in most installations such as the cylinder of Figure l eliminates the need for special cushioning means such as sleeves 50 and 52 acting in conjunction with recesses 36 and 38 although they do not prevent the incorporation of such additional cushioning means in installations where they are desired.

M The assembly of piston 14 requires only the insertion of the piston body 14 over the end 46 of the piston rod 16 and the securing'of it in place with nut 54 between cushion sleeves 50 and 52 if they are provided. Such assembly is more economical of time and parts than previous assemblies requiring spacing rings, retainer plates and separate sealing cups to be secured together to close tolerances. Also, the possibility of distortion of flange 56 in assembly is substantially reduced.

Operation of the cylinder 12 with piston 10 therein is in the usual manner as previously indicated. A hydraulic or pneumatic medium is forced under pressure into one part 66 of piston chamber 34 through orifice 42 and is exhausted from the other part 68 through orifice 40 by means not shown to cause the piston 10 and rod 16 to move to the left in Figure 1. The reverse flow of the medium will cause the piston and rod to move to the right. The actuating pressure acting on the piston 10 in conjunction with the cup shape and thin outer portions 59 and 61 of flange 56 causes the flange to firmly press against cylinder body 20 to facihtate the sealing action therebetween. At the end of each stroke of the piston, projections 58 contact end closures 22 and 24 of the cylinder 12 cushioning such contact thereby removing the necessity of special cushioning means such as sleeves 50 and 52 in many installations. The drawing and the foregoing specification constitute a description of the improved unitary sealed piston in such full, clear, concise and exact termsas to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is: '1. A unitary sealed 'pi'ston comprising a cylindrical body member and a resilient member including sealing and cushioning means sealed to said body member to provide a piston seal and cushion the piston in operation, said cushioning means comprising a plurality of angularly spaced axially extending resilient projections integral with said resilient member and spaced radially inwardly from the outer periphery thereof.

2. A unitary sealed piston comprising a core of circular cross section and a single resilient sealing member having a first wall portion located at the radially outer edge of said core and a second wall portion extending radially inwardly from said first wall portion and engaging the edge portion of said core, said first wall portion of said resilient sealing member including a relatively thin walled flexible annular axial flange adapted to sealingly engage the inner surface of a cylinder in which said piston is mounted, said second wall portion including cushioning means to cushion said piston at the end of the stroke thereof during operation, the radially outer surface of said resilient sealing member being concave outwardly to produce annular sealing zones adjacent the edges thereof.

3. A unitary sealed piston comprising a core of circular cross section and a single resilient sealing member bonded to said core including a first wall portion located at the radially outer edge of said core and a second wall portion extending radially inwardly from said first wall por tion and engaging the edge portion of said core, the radially outer surface of said first wall portion being concave outwardly to produce annular sealing zones adjacent the edge thereof, said second wall portion including cushioning means to cushion said piston at the end of the stroke thereof during operation.

4. A unitary sealed piston comprising a flat disk and a single annular resilient sealing member having a 'generally U-shaped cross section including a bottom wall portion located at the radially outer edge of said disk and side Wall portions extending radially inwardly from said bottom wall portions and engaging opposite sides of the edge portion of said disk, said bottom wall portion of said sealing member including relatively thin walled flexible annular oppositely extending axial flanges adapted to sealingly engage the inner surface of a cylinder in which said piston is mounted, said side wall portions including cushioning means to cushion said piston at the end of the stroke thereof during operation.

5. A unitary sealed piston comprising a flat disk and a single annular resilient sealing member having a generally U-shaped cross section including a bottom wall portion located at the radially outer edge of said disk and side wall portions extending radially inwardly from said bottom wall portions and engaging opposite sides of the edge portion of said disk, said bottom wall portion of said sealing member including relatively thin walled flexible annular oppositely extending axial flanges adapted to sealingly engage the inner surface of a cylinder in which said piston is mounted, said side wall portions including cushioning means to cushion said piston at the end of the stroke thereof during operation, comprising a plurality of angularly spaced axially extending resilient projections integral with said resilient sealing member.

6. A unitary sealed piston as claimed in claim 2 wherein the annular resilient sealing member is generally U- shaped in cross-section.

7. A unitary sealed piston as claimed in claim 2 wherein the resilient sealing member is bonded to the core.

8. A unitary sealed piston as claimed in claim 2 where in the cushioning means is located radially inwardly from the axial flange.

9. A unitary sealed piston as claimed in claim 2 wherein the'cushioning means extends axially beyond the axial flange.

10. A unitary'scaled piston comprising a core of circular'crosssection and a 'single resilient sealing member secured to said core including a first wall portion located at the radially outer edge of said core and a second wall portion extending radially inwardly from said first Wall portion and engaging the edge portion of said core, the radially outer surface of said first wall portion being concave outwardly to produce annular sealing zones adjacent the edge thereof, said second wall portion including cushioning means to cushion said piston at the end of the stroke thereof during operation.

References Cited in the file of this patent UNITED STATES PATENTS 723,025 Resor Mar. 17, 1903 6 Lamb Mar. 23, Christenson June 4, McQuaid June 25, Roth Sept. 10, Christensen Nov. 11, Miller June 23, Carey Dec. 16, Stevens June 23, Browall June 24, Pauly May 5, McConnaughey July 21, Dibley et a1 Nov. 17, 

